So you have a Javascript array, and you want to get the last element. Take this example, for instance:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]

This array has 4 items - and as you might know, to get any element within it, we can use the square bracket notation []. For example, to get the lighting bolt, we can use myArray[1]:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]
console.log(myArray[1]) // ⚡️

Since arrays start at an index of 0, the first element is actually myArray[0], and so on. So to get the last element of the array, we can use myArray.length - 1. This gets the length of the array (4), and subtracts 1, to take into consideration that arrays start counting at 0. Therefore, to get the last element of an array using the square bracket notation, we can do something like this:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]
console.log(myArray[myArray.length-1]) // 🖇

This is the most common way to get the last element of an array. However, you can also use the at method to do the same thing:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]
console.log(myArray.at(myArray.length-1)) // 🖇

And even better, you can simply write myArray.at(-1)! This greatly simplifies getting the last element of an array to a simple expression:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]
console.log(myArray.at(-1)) // 🖇

As you might expect, at starts counting backwards, so at(-2) will return the key:

let myArray = [ '🔩', '⚡️', '🔑', '🖇' ]
console.log(myArray.at(-2)) // 🔑